Densitometry is a field where the optical density of a fluid specimen is measured by providing a light source and a detector with the detector detecting the amount of light transmitted through the specimen. In more advanced forms of densitometry, the light is limited to a narrow band of light frequencies. Multiple densitometer readings are obtained at different light frequencies to learn more about the specimen being examined.
To efficiently analyze multiple specimens as quickly and reliably as possible, a microtiter plate is often utilized with a plurality of wells therein arranged in rows and columns. The microtiter plate is substantially planar and is typically oriented substantially horizontally to keep the specimens within the wells of the microtiter plate MTP. One such arrangement of microtiter plate is shown in FIG. 2.
Furthermore, to efficiently analyze specimens within separate wells of the microtiter plate, a single light source can be divided through known prior art equipment into separate light sources, such as through the use of fiber optic light conductors each feeding a single light source to multiple separate wells. Using known prior art equipment, such as that depicted in FIG. 1, a single light source such as a halogen lamp 2 is provided. An infrared filter 4 can be utilized to remove infrared portions of the spectrum, to remove heat containing portions of the spectrum from the light being emitted from the lamp 2. An interference filter 6 is utilized to absorb all light frequencies other than those particularly desired for a measurement being conducted by the densitometer. In some more advanced systems, multiple interference filters 6 are provided which can be selectively positioned in line with the lamp 2 so that different frequencies of light are allowed to pass onto the light conductors 8.
Detectors 9 are provided below the wells in the microtiter plate MTP so that the liquid L contained within the wells W is separately measured by the detectors 9. Typically, the interference filter 6 limits the wavelength to −5 to +5 nanometers of the desired wavelength. Depending on the nature of the liquid L, more or less of the light is absorbed. Under the well W, the non-absorbed light is captured and conducted to the detector 9. The luminous intensity is measured and the absorption can be calculated. Multiple wells W are measured simultaneously with such prior art densitometers, so that the densitometer can act multiple times faster depending on the number of light conductors 8 utilized and the size of the microtiter plate MTP.
While generally effective, one problem with such densitometers is the potential for light from adjacent light conductors to have some influence on the luminous intensity read by each detector, such that otherwise properly calibrated detectors might detect a greater intensity than is actually passing through the specimen because it is hitting the detector at least partially from one of the other light conductors. Furthermore, with the prior art multiple interference filters are required and mechanisms for adjusting the interference filters so that proper frequency light is utilized for the particular densitometer test being conducted. These details add complexity to the densitometer and slow down the process Accordingly, a need exists for further enhancement of the efficiency and reliability of densitometer systems and methods.